751 research outputs found
Introduzione
No full textIl prodotto introduce al pubblico italiano l'opera Grasshopper (b. Suits), che svolge un ruolo definitorio fondamentale nella disciplina dei Game Studie
Gioco per l'età libera. L'esperienza del Laboratorio di gioco per anziani di Lusory Warp
No full textIl prodotto descrive l'ideazione del Laboratorio di Gioco per Anziani, dettagliando la metodologia, il progetto con le criticità legate alle problematiche dell'età avanzata e l'esperienza generata, con conclusioni basate sull'osservazione partecipata e i dati qualitativi raccolti
Two-Dimensional Beam Tracing from Visibility Diagrams for Real-Time Acoustic Rendering
No full text We present an extension of the fast beam-tracing method presented in the work of Antonacci et al. (2008) for the simulation of acoustic propagation in reverberant environments that accounts for diffraction and diffusion. More specifically, we show how visibility maps are suitable for modeling propagation phenomena more complex than specular reflections. We also show how the beam-tree lookup for path tracing can be entirely performed on visibility maps as well. We then contextualize such method to the two different cases of channel (point-to-point) rendering using a headset, and the rendering of a wave field based on arrays of speakers. Finally, we provide some experimental results and comparisons with real data to show the effectiveness and the accuracy of the approach in simulating the soundfield in an environment.</p
Giocare ancora. Un’esperienza di laboratorio di gioco con gli anziani
No full textIl prodotto descrive la metodologia di progetto dell'esperienza "Laboratorio di gioco per gli anziani", l'esperienza stessa nella struttura delle sue fasi e le conclusioni tratte dall'osservazione partecipata e dall'analisi qualitativa svolta
Field observations and failure analysis of the Basilica S. Maria di Collemaggio after the 2009 L'Aquila earthquake
No full textOn Monday, the 6th of April, 2009, a devastating earthquake struck L'Aquila causing the partial collapse of the Basilica S. Maria di Collemaggio, an important symbol of the city. The mechanism of the transept structure's failure, which left the external boundary walls almost undamaged, probably due to the sudden collapse of the large multi-lobed pillars at the end of the nave, is discussed in the paper by different points of view. A brief historical review of the monument restorations is followed by the analysis of the damage scenario recorded during the post-earthquake inspections. Finite element models of the Basilica, updated on the basis of available dynamic tests, have been used to perform a seismic assessment by response spectrum analysis according to the current Italian code, showing a high vulnerability, in the transversal direction larger than in the longitudinal one. The AQK earthquake accelerograms, recorded close to the site, have evidenced a prevailing component almost aligned with the longitudinal Basilica axis; the intensity is comparable with the one provided by the code, with exception in the vertical one greater than expected. Static nonlinear analyses have furnished the crack propagation in the masonry walls due to the increase of longitudinal horizontal loads. The presented failure description obtained by structural modeling is coherent with the direction of the registered polarized seismic action and it is compatible with the observed damage and with most of the debris positions coming from the collapse of the transept structures. (C) 2013 Elsevier Ltd. All rights reserved.On Monday, the 6th of April, 2009, a devastating earthquake struck L’Aquila causing the partial collapse of the Basilica S. Maria di Collemaggio, an important symbol of the city. The mechanism of the transept structure’s failure, which left the external boundary walls almost undamaged, probably due to the sudden collapse of the large multi-lobed pillars at the end of the nave, is discussed in the paper by different points of view. A brief historical review of the monument restorations is followed by the analysis of the damage scenario recorded during the post-earthquake inspections. Finite element models of the Basilica, updated on the basis of available dynamic tests, have been used to perform a seismic assessment by response spectrum analysis according to the current Italian code, showing a high vulnerability, in the transversal direction larger than in the longitudinal one. The AQK earthquake accelerograms, recorded close to the site, have evidenced a prevailing component almost aligned with the longitudinal Basilica axis; the intensity is comparable with the one provided by the code, with exception in the vertical one greater than expected. Static nonlinear analyses have furnished the crack propagation in the masonry walls due to the increase of longitudinal horizontal loads. The presented failure description obtained by structural modeling is coherent with the direction of the registered polarized seismic action and it is compatible with the observed damage and with most of the debris positions coming from the collapse of the transept structures
Terrorismo, educazione e fraternità. Una sfida per la comunità
No full textIl contributo vuole proporre una connessione tra i termini di terrorismo, educazione e fraternità, nel riconoscimento del ruolo fondamentale che il pensiero pedagogico e la prassi educativa possono giocare nella costruzione o nella decostruzione di questi legami
Special Issue: A Tale of Genes and Genomes
No full textVariability is the source on which selective pressure acts, allowing genome evolution and adaptation [...
Closed geodesics on compact Lorentzian manifolds of splitting type
No full textIn this paper, we consider the problem of the existence of a spacelike closed geodesic on compact Lorentzian manifolds. Tipler and Galloway proved that, under suitable topological properties of the manifold, there exists a closed timelike geodesic. In their proofs, they use the hypothesis that the time coordinate of one timelike geodesic has derivative always different from zero. This clearly fails for spacelike geodesics. Using variational methods and applying the relative category theory, we prove the existence of a closed spacelike geodesic on a compact manifold script M sign of splitting type. Observe that, thanks to the previous results, the existence of at least two geometrically distinct closed geodesics on script M sign follows
Some results about geodesics on lorentzian manifolds of splitting type
No full textLet us consider a Lorentzian manifold (M,g), that is a smooth, connected, finite-dimensional manifold M endowed with a smooth symmetric second order metric tensor field g, having index 1. For any z in M, it induces on T,M a nondegenerate bilinear form g(z)[., .] having exactly one negative eigenvalue. In order to study the geometry of (M,g) geodesic curves play an important role. We recall that a geodesic is a smooth curve 7: [0, l] + M which satisfies the equation:
v,j-0,
where V,+(s) denotes the covariant derivative of 7(s) with respect to the Levi-Civita connection of the metric tensor g. A closed geodesic is a geodesic 7 such that
r(O) = 7(l) and %O) = ?(I).
It is well known that if 7 is a geodesic, there exists a constant E-, such that E-, = g(7(s))[j(s),j(s)]
for all s E [0, l] . Then 7 is said timelike, lightlike or spacelike respectively when E, is negative, null or positive.
The aim of this paper is to review some recent results concerning some properties of geodesics on a Lorentzian manifold. Particularly we will analyse two questions: the existence of closed geodesics and the geodesical connectedness for some classes of Lorentzian manifolds. We recall (M, g) is said geodesicallyconnectedif every couple of its points can be joined by a geodesic.
The results here reported are obtained by means of global variational methods and relative category theory and they refer to [l], [2], [4], [5], [6], [12], [13], [15].
The paper will be divided into two sections, dealing separately with the previous problems
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